NEVER forget to shave this down!

Why are mechanics drilling into a perfectly good engine block?! ⚙️🏁
If you want to make massive horsepower, you need to install a high-performance camshaft! A bigger camshaft pushes the engine valves open much further, letting more air and fuel into the cylinders. However, there is a hidden danger! Because the valve is pushing down deeper into the engine, the metal components can physically crash into the factory valve guides!
To prevent the engine from destroying itself, mechanics use a specialized cutting tool to machine down the tops of the cast-iron valve guides. After shaving the metal down for proper clearance, they lubricate the fresh surface and press on a brand new, heavy-duty valve stem seal. This precise machining guarantees the engine can handle the massive new camshaft without crushing the seals!